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// ---------------------------------------------------------------------------
// Copyright:   (c) 2021 ff. Michael Amrhein (michael@adrhinum.de)
// License:     This program is part of a larger application. For license
//              details please read the file LICENSE.TXT provided together
//              with the application.
// ---------------------------------------------------------------------------
// $Source: src/errors.rs $
// $Revision: 2022-04-06T15:51:25+02:00 $

use core::fmt::{Debug, Display, Formatter};

/// An error which can be returned from converting numbers to `Decimal` or from
/// binary operators on `Decimal`.
///
/// This error is used as the error type for the `TryFrom` implementation of
/// `Decimal`. It is also used when the implementations of the numerical
/// operators panic.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum DecimalError {
    /// More than [MAX_N_FRAC_DIGITS](crate::MAX_N_FRAC_DIGITS) fractional
    /// decimal digits requested.
    MaxNFracDigitsExceeded,
    /// The result would exceed the internal representation of `Decimal`.
    InternalOverflow,
    /// Attempt to convert an infinite value to `Decimal`.
    InfiniteValue,
    /// Attempt to convert a 'not-a-number' value to a `Decimal`.
    NotANumber,
    /// A division op called with a divisor equal to zero.
    DivisionByZero,
}

impl DecimalError {
    #[doc(hidden)]
    #[must_use]
    pub const fn _description(&self) -> &str {
        match self {
            Self::MaxNFracDigitsExceeded => {
                "More than MAX_N_FRAC_DIGITS fractional decimal digits \
                 requested."
            }
            Self::InternalOverflow => "Internal representation exceeded.",
            Self::InfiniteValue => "Can't convert infinite value to Decimal.",
            Self::NotANumber => "Given value is not a number.",
            Self::DivisionByZero => "Division by Zero.",
        }
    }
}

impl Display for DecimalError {
    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self._description(), f)
    }
}

#[cfg(feature = "std")]
impl std::error::Error for DecimalError {}